It doesn't matter whether you are 21 or 71, you can change your body into what you want it to be. Getting into shape involves four things:
1. Doing the right exercises.
2. Lifting progressively heavier weights over time.
3. Eating correctly.
4. Giving your body enough rest between workouts.
If you decide to start, I can guarantee you're going to learn to love it. You are going to meet your goals. You are going to get stronger, both physically and mentally. You are going to get a little bit closer to the person that you want to be.